Pool Pump Service Factor and Total Horsepower

Service factor as a listing word

A pool pump listing can name a service factor figure alongside the horsepower. The service factor is a multiplier found on the motor nameplate; it describes how much sustained output the motor's stated base horsepower can deliver beyond the base figure. When a listing shows a service factor figure, it is the seller's stated word for that multiplier, not an independent measurement.

As a listing term, the service factor appears as a label with a figure, sometimes in the title and often in the bullet list. The site reads the figure as the seller declares it and compares listings on the stated details. The guide to reading a pool pump listing explains where horsepower and related figures sit in a title.

What total horsepower means

THP stands for total horsepower. On a pump listing, THP is the stated output figure that results from applying the service factor to the stated horsepower. Some listings show only the THP figure and skip the base figure; others show both. The THP figure is a seller's declaration, and a listing that names it gives you the stated total output rather than the base figure alone.

Makers also use wording such as "true HP" to label the figure they want buyers to notice. The Pentair pool products page, for example, lists THP as a product filter attribute, which shows that total horsepower is a common way for sellers to organize pumps by stated output. The difference between motor horsepower and THP is explained in a separate guide.

Reading SF and THP in a pump title

A pump title can carry several horsepower words at once: a base horsepower figure, a service factor figure, and a THP figure. When the title shows two figures, the model name usually carries the base horsepower and the feature words carry the THP or service factor label. The title is read as a set of seller statements; the manual has the full stated details.

A title that names THP is telling you the stated total output of the motor. A title that names only the base horsepower is giving you a partial figure. Comparing the two kinds of titles means comparing the figures each listing states. The guide on horsepower versus THP looks at how the two terms differ in a listing.

Why the figures matter for shopping

When comparing pumps, the stated horsepower and the stated THP figure give you two ways to read the same motor. Two listings with the same base horsepower may declare different THP figures, and a listing that names THP is giving you the declared output after the service factor is applied.

The site's guide bands group pumps by the stated horsepower figures in their titles. A pump in the 2 HP and up band is a pump whose listing states a horsepower figure in that band. The THP figure is read the same way: as the seller states it in the listing.

The service factor figure is part of the listing's stated details, and this site compares listings only on what the seller declares. The maker's manual is the place to find the full stated figures for the same motor, including the service factor and the THP figure in the context of the model's full specification.

Service factor and pool sizing

The site matches no service factor figure and no THP figure to a pool volume, a filter size, or a run time. Service factor and total horsepower explain how the motor's output is stated, not how the pump performs on a specific pool. The maker's sizing page and an installer decide the match for a particular pool.

Horsepower figures appear in different forms across the pool pump industry. The ENERGY STAR pool pump criteria, for example, reference a hydraulic horsepower figure in their efficiency levels, which is a different figure from THP but another example of how horsepower words vary by context. ENERGY STAR is a program that certifies pool pumps that meet its efficiency criteria, as described on the program's own pages.

Buying a pump with a stated output that is much larger than the pool needs is a separate question. The article on oversizing a pool pump explains what oversizing means in a listing.

Questions to ask before buying

Before choosing a pump, collect the stated figures from the listing and the manual, then take the pool's details to the maker's sizing page and an installer. These questions keep the comparison on the listed details:

• What horsepower figure does the listing state, and is it labeled as base horsepower, THP, or both?
• Does the title carry a service factor figure, and where does the manual place it?
• What does the maker's sizing page recommend for the pool's stated size and filter?
• What does an installer recommend before the pump is connected to the pool's plumbing?

What to pick for your situation

Questions

Is THP the same as horsepower?

THP is the stated total horsepower figure on a listing, often after the service factor is applied to the base horsepower. The two words are not interchangeable: THP names the stated total output, while horsepower can name the base figure.

Why does a pump listing show two horsepower figures?

A listing can show the base horsepower and the THP figure separately. The base figure and the THP figure describe the same motor in two ways, and the THP figure states the output after the service factor is included.

Does a higher service factor mean the pump moves more water?

A higher service factor states a larger total output for the motor. Whether that output suits a pool is a question for the maker's sizing page and an installer; the site makes no match between service factor and pool size.

How do you know if a pump with a certain THP fits your pool?

The listing states THP as a seller's figure. Matching it to a pool requires the maker's sizing page and an installer's advice; this site does not match pumps to pool sizes.

Should you compare pumps by horsepower or by THP?

Compare the figures each listing states. A listing that names THP gives you the stated total output; a listing that names only base horsepower gives you one figure. Look for the manual's stated figures and compare like for like where you can.